1. Field of the Invention
The present invention relates to an improved needle holder assembly and, more particularly, a needle holder assembly having a release mechanism for smoothly releasing the needle holder from a retracted position to permit the needle holder to slide within a sleeve to an extended position at which the holder is permanently locked for disposal by an improved locking mechanism.
2. Background Description
A needle holder assembly is commonly used in hospitals and doctors offices to aid in drawing body fluid, e.g., blood, from a patient for diagnostic testing and other procedures. Needle holder assemblies primarily consist of a hollow cylinder inner tube body or needle holder that holds a standard double-ended hollow needle at its distal end with one end of the needle extending into the tube and the other end extending out of the tube for piercing the patient's skin extending. The tube body is shaped to receive an evacuated collection tube having a piercable closure so that the closure is pierced by the internal end of the needle and body fluid is drawn by the vacuum from the patient into the collection tube. An example of a piercable closure that is currently being used to seal evacuated tubes is the HEMOGARD.TM. Closure for use on the VACUTAINER Brand tube from Becton, Dickinson and Company. The HEMOGARD.TM. Closure is basically a rubber stopper covered by a plastic shield, however, a more detailed description of the closure is contained in U.S. Pat. Nos. 4,741,446 (Miller) and 4,991,104 (Miller), both of which are assigned to Becton, Dickinson and Company and incorporated herein by reference.
Needle holder assemblies have also been made having an outer safety shield or sleeve that slidably receives the hollow cylinder inner tube, described above, the sleeve being slightly larger in diameter than the inner tube which permits the inner tube to slide within the sleeve from a retracted position to an extended position. When the inner tube is in the retracted position, the needle extends out of an opening in the distal end of the sleeve and when the inner tube is in the extended position, the needle is contained within and surrounded by the sleeve so that the needle holder assembly can be disposed of. Such needle holder assemblies are very useful and valuable since they minimize the chance of accidental needle sticks occurring after the assembly has been disposed of by surrounding the sharp point of the used needle.
A needle holder assembly of the type described above is shown in U.S. Pat. No. 4,923,445 (Ryan). The Ryan assembly includes a hollow cylindrical inner tube body with a needle at its forward end and an outer shield arranged to slidably receive the inner tube body. The inner tube slides from a retracted position to an extended position and includes a locking mechanism to lock the shield in the extended position. The locking mechanism, however, does not permanently and securely lock the inner tube and sleeve together, since it merely retains the inner tube in the retracted position by using solid protrusions on the wall of the shield to engage a groove on the inner tube. However, the protrusions can easily be disengaged from the groove using moderate force and some wiggle. Therefore, the Ryan assembly does not provide the secure permanent locking action that is required to safely dispose of a used holder, since the holder could be pushed easily towards the retracted position and expose the needle beyond the shield. Another disadvantage of the Ryan assembly is that it is difficult to disengage from the retracted position, since rotation of the inner tube is prevented by a ratchet mechanism that locks the inner tube and shield together when the assembly is in the retracted position.
U.S. Pat. No. 4,947,863 (Haber et al.) and Re. 33,585 (Haber et al.) also describe collection tube holders like those discussed above. The Haber et al. holders also include a shock absorbing system with deceleration stations that absorb and dampen vibrations that are generated by the jarring impact forces when the outer sleeve is advanced and locked in the extended position. However, the Haber et al. holders do not address the need for permanently and securely locking the inner tube to the sleeve at the extended position or providing a release mechanism for smoothly releasing the inner tube from the retracted position.